Ventilator blast closure



Dec. 25, 1962 J. R. ALLGOOD ETAL 3,069,993

VENTILATOR BLAST cLosURE Filed June 7, 1960 2 Sheets-Sheet 1 F/GJ.

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JAY R. ALLGooD Rosen E SWALLEY JNVENToRs BVMW A T TOR/VE Ys United States Patent Otltce lhggfi Patented Dec. 25, i952 3,tia9,993 VENTLATR C .lay RHAllgood, Semis, and Robert i?. Swaiiey, Ventura,

Calir., assignors to the United States of America as represented by the Secretary or the Navy Filed .lune 7, i960, Ser. No. 34,5%

(Granted under Title 3S, US. Code (H52), sec. 2de) The invention described herein may be manufactured and used by or for the Goverment of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates generally -to the ventilation of underground personnel shelters for use in the vicinity of possible nuclear bomb attacks and specifically to a ventilating closure which may be primarily actuated by the bomb blast itself.

One of the most important considerations in the design of underground shelters for use in the protection of personnel from nuclear attacks is adequate ventilation. Normally, such ventilation may be provided by one or more ventilation pipes or ducts reaching from the shelter to the surface of the ground above. In the event of the explosion of an atomic bomb within effective ranges of the shelters, some provision must be made to immediately seal-off the above ground ventilation duct opening. Such sealing-o provision should, for maximum protection, be triggered by functions of the blast itself, either light or pressure. When the worst effects from the nuclear bomb have passed on over the location of the shelter, some means must be provided for opening the closure device from inside the shelter as the surface would still be dangerous from radioactive fallout or other effects from the bomb. A certain amount of pressurization from bottled air or oxygen could be provided in the shelter to prevent the ingress of infected air through the ventilation duct.

The object of this invention, therefore, is to provide a ventilator blast closure for the Ventilating ducts of underground bomb shelters which closure may be actuated remotely.

A further object of lthis invention is to provide such ventilator blast closure with means so that it may be automatically actuated into the closing position by a function or effect of the nuclear blast itself.

Another object of this invention is to provide a ventilator blast closure that may be opened remotely from within the underground shelter.

Other objects and advantages of this invention will be appreciated in conjunction with the following detailed o description and accompanying drawing wherein:

FIGURE l is a partially cross-sectional elevation of the underground shelter showing the ventilation duct and the blast closure therefor; v

FIG. 2 is a cross-sectional side elevation of the invention showing the device in open position;

FIG. 3 is a similar view showing the device in the closed position;

FIG. 4 is a. sectional plan View taken on the line -li of FIG. 3;

FIG. 5 is a cross-sectional front elevation;

FIG. 6 is a detail view of a portion of the invention; and

FIG. 7 is a schematic diagram of the electrical circuitry used in the invention.

With reference to FlG. l showing the general arrangement, the underground shelter 10 may be constructed of reinforced concrete with a hemispherical root il and end walls 12. A heavy door 13 is provided in one of the end walls which opens from the shelter into a protected horizontal passage 14 which, in turn, communicates with a laddered vertical shaft 15. This latter shaft or passage may be covered with a heavy cover i6 which may be hinged or otherwise arranged for being secured in place by the last person descending shaft l5.

A Ventilating duct 17 communica-tes with the interior of the shelter through the other end wall l2 and is extended upwardly until it rises just below the surface of the ground over the shelter. The blast closure Ztl is placed over the upper end of the duct 17 and may be flush with the surface 18 or extend slightly above it as shown. The blast closure Ztl may be secured to the duct by welding or other mode of fastening or may be held in place by securely tamping the earth around it.

With reference now to FIGS. 2 to 6, inclusive, blast closure 2l) comprises a hollow cylindrical standpipe 215 and a hinged hemispherical lid 2S adapted to lit snugly over the end of the pipe 22 and be sealed thereto. O-ring 29 is fitted into the lower edge of the lid 2d for providing the seal between the lower edge of the lid and the upper machined surface of the pipe 22. Hinge bar 23 may be welded or otherwise suitably secured to the upper end of the pipe 22. Hinge 3@ may be so secured to the lid 28 so as to cooperate with the hinge bar 23. Hinge pin 31 holds the two hinge parts together. Lug 32 is welded or secured to the lid opposite the hinge 31d and may be used to lift the lid manually or, in conjunction with lug 24, may be used to clamp the lid onto the top of pipe 22 as during periods of non-use of the shelter.

Diametrically opposed hook eyes 33 are welded or otherwise suitably secured to the inside of the lid ou a line normal to the line passing through hinge Sti and the lug 32. Corresponding hook eyes 25 are secured to the walls of the pipe 22. Secured to and stretched between corresponding hook eyes 33 and 25 are two heavy tension springs 34. These springs are heavy enough and are under sufficient ytension to hold the lid securely in sealing relationship with the top of the pipe 22 under the effects of the high pressure from the bomb blast and also from the negative pressure phase when the external pressure is reduced to a low level and the pressurized air in the shelter would otherwise tend to force the lid open.

Trigger 35 is provided to hold the lid 28 open against the tension of the springs 34. This trigger is pivotally supported by hinge 36 which may be welded to the inside wall of the pipe 22. Trigger and its associated hinge are installed in line with the diametrical line established by hinge bar 23 and lug 24. The upper end of the trigger is notched, as shown, to conform to a similar notch in the trigger sector 37 which latter part is welded on to the inner wall of th-e lid 28. Thus, the horizontal surface 3d on the upper portion of the trigger cooperates with the lower horizontal surface 39 of the trigger sector 37 and the corresponding inclined vertical surfaces dit and il mate to hold the lid open. When the trigger is forced into the vertical position as will be explained later, the surfaces previously mentioned disengage and trigger surface E@ is disposed adjacent to sector horizontal surface d?. and trigger inclined surface d@ engages sector inclined surface 453.

Trigger 35 is provided with a cross-bar ifi to the ends of which are secured two tension springs d5. The other ends of these springs `4S are secured to small hook eyes 46 which may be threaded into holes in the inner side of the pipe 22. These springs l5 urge the trigger outwardly so that when the lid is raised from the closed position (FIG. 3) to the open position (Fl-G. 2), the trigger moves outwardly to engage the lower surfaces of the trigger sector in the lid so as to hold it open.

rfwo bores are provided in the trigger and trigger sector for holding explosive charges d@ and 5l. The bore for epesses the explosive charge 5@ in the trigger is formed normal to the trigger horizontal surface 33. The bore for the explosive charge 51 in the trigger sector of the iid is formed normal to the sector inclined vertical surface `4l.. Thus, when the lid is in the open position (EEG. 2) and explosive charge 5l is set off, the expanding gases or the shock wave from charge 51 impinges on trigger inclined surface #itl and forces the trigger to the left against the stop S5 as shown bythe dotted lines. rl' he springs then force the lid down on top of the pipe 22 in sealing relationship. When it is desired to open the blast closure from the closed position (HG. 3), explosive charge in the trigger' is set ofi and the expanding gases or the shock wave from charge 5d impinges vertically against the horizontal sector surface 42 thus forcing the lid upward. As the latter occurs, the trigger swings to the right under the luence of the tension springs 4S to engage sector lower surface 39, and the lid is held open again. After the emergency has passed, lid 2S may be manually opened and the expanded explosive'charges Sil and 51 may be replaced.

One type of circuitry which may be used for exploding the explosive charges Sil and Si is schematically indicated in 7. lie circuit comprises a photoelectric relay circuit 7i? including a photoelectric tube or cell 71. and the normally open switch relay 72. A pressure actuated normally open switch '73 may be provided in parallel with relay '72. As either or both switches are closed, electric current is introduced into the detonating cap of charge 5l and it is then exploded. It isvunderstood, of course, that, though not shown, photoelectric cell 71 and pressure actuated switch 73 are located on the ground surface in the proximity of the buried shelter with leads leading into the shelter or the pipe 22 and connected to the closing explosive charge Si. The circuit for exploding the opening charge Sil merelytincludes a source of EMF. and a normally open manually operated switch '74.

EEG. 6 suggests one possible way of electrically exploding `the charges 5? and Si. Additional side bores 52 and S3 are provided in sector 37 and trigger 35 which intersect the bores holding the charges 5l and 5d. Electrical detonating caps may be placed and connected to the leads 54 and 56. Other methods of electrically setting off the explosive charges 5t) and 51 may be utilized.

Having thus described and illustrated a preferred embodiment of our invention, we do not intend to be limited thereby. Many modifications may suggest themselves to those skilled in the art. It is considered that all such modifications may `well fall within the spirit of our invention and the scope of the appended claims wherein we claim as new and desire Letters Patent thereon:

1. A blast closure for the Ventilating ducts of underground protective shelters located in the vicinity of high order explosive blasts comprising, in combination:

a hollow standpipe adapted to lit over the upper end of said Ventilating duct;

a lid hingedly pivoted on the upper end of said standpipe and adapted to sealingly engage said upper standvpipe end;

resilient means for holding said lid in sealing relationship with said upper standpipe end;

a trigge sector secured to the lower inner si-de of said lid, said trigger sector having a notched configuration consisting of two upper and lower substantially hori- Zontal surfaces and two upper and lower substantially vertical surfaces;

a trigger pivotally supported in the interior of said standpipe and extending substantially vertically thereof, the upi er end of said trigger having a notch consisting of one substantially horizontal surface and one substantially vertical surface, said trigger surfaces mating with the corresponding surfaces on said trigger sector whereby when said trigger notch mates with the lower surfaces of said trigger sector, said lid is held in the open position and when said trigger notch mates with the upper surfaces of said trigger sector, said lid is positioned in sealing engagement with the upper end of said standpipe;

a bore in said trigger sector normal to .the lower oi said substantially vertical suifaces;

an explosive cartridge contained insaid bore; and

means responsive to said high order explosive blast for actuating said explosive cartridge whereby said trigger is forced away from said trigger sector and said lid is forced into sealing engagement with the upper end of said standpipe.

2. A blast closure as claimed in claim l further characterized by said trigger having a bore normal to the substantially horizontal surface of said trigger notch;

an explosive cartridge contained in said trigger bore;

manually operated electrical means located in said underground structure for actuatingrsaid explosive cartridge; and

resilient means connected betweensaid trigger and the interior wall of said standpipe for forcingsaid trigger toward said standpipe wall whereby, when said lidis in closed position and said trigger notch mates with the upper surfaces of said trigger sector, said lid will be forced open by. the explosion of said explosive cartridge, and said trigger notch will be .moved to mate with the lower surfaces of said trigger sector and said iid will be held in open position.

3. A blast closure as claimed in claim 1 wherein said means responsive to said high order explosive blast include light and pressure responsive devices sensitive to the phenomena of light and pressure Waves created bysaid high order explosive blast.

References Cited in the iile of .this patent UNlTED STATES PATENTS 1,882,700 Allen Oct. 18, 1932 2,334,121 Olshin Nov. 9, 1943 2,350,162 Fairbanks May 30, 1944 FOREIGN PATENTS 63,319 Norway Dec.'29, 1941 854,836 Germany Nov. V6, .1952

OTHER REFERENCES Publicationtby Conax Corporation (a paper presented at the American Rocket Society, September 24, 1956), 7 pages; page 7 only. 

